A SYSTEM FOR CONTROLLING AND ENFORCING PLAYBACK RESTRICTIONS FOR A MEDIA FILE BY SPLITTING THE MEDIA FILE INTO USABLE AND UNUSABLE PORTIONS FOR PLAYBACK

Files are divided into parts and at least some of the parts are transmitted to a client using a communication channel. At least some of the transmitted parts are cached locally. This allows subsequent streaming playback of the file while using less bandwidth by transmitting the part of the file that hasn't been cached, and combining the cached parts with the transmitted parts. In some embodiments, files may be represented at a low quality level by a first data set, and at higher quality levels with additional data sets. Data sets are cached locally, so that during subsequent streaming playback of the file, the quality level of the playback may be improved by sending additional data sets using bandwidth that would otherwise be dedicated to transmitting the cached data sets.